Hi - I'm a female master's runner (just turned 44) looking to improve my time in the 5K. I started back into running a couple years ago after almost 20 years out of racing (used to run in high school and did a year of college xc and track) and have cut my time down from about 26 minutes to the high 21 minute range during last two years. I run about 25 miles a week now - no speedwork yet just some tempo runs, a long run and basic mileage - not sure about the best approach to take next. Any ideas?